1. Field
Aspects of the present invention relate to a secondary battery, and more particularly, to a secondary battery capable of preventing an electrode assembly from vibrating without an insulating case.
2. Description of the Related Art
Recently, various batteries are used as the power sources of small electronic apparatuses. In particular, batteries such as lithium secondary batteries (which are small) and large capacity sealed type batteries are mainly used as the power sources of the small electronic apparatuses, such as mobile telephones, laptop computers, and camcorders, or other similar small electronic apparatuses.
A jelly-roll electrode assembly is obtained by coating a positive electrode collector and a negative electrode collector with an active material. A separator is interposed between the positive electrode collector and the negative electrode collector. The positive electrode collector and the negative electrode collector interposed with the separator are then wound. The jelly-roll electrode assembly is accommodated in a battery can, an electrolyte is injected into the battery can, and the battery can is sealed in order to form a lithium secondary battery. A cylindrical battery, in which an electrode assembly is accommodated in a cylindrical battery can, and a polygonal battery, in which an electrode assembly is accommodated in a square battery can, are commonly used.
Since the electrode assembly of the battery is wound around itself, a closing tape is attached onto the external surface of the electrode assembly in order to secure the electrode assembly in closing the electrode assembly. The electrode assembly onto which the closing tape is attached is accommodated in the can, the electrolyte is injected into the can, and the upper end of the can is sealed using a cap assembly.
At this time, the electrode assembly consists of a jelly-roll having a positive electrode plate, a negative electrode plate, a separator disposed between the positive electrode plate and the negative electrode plate and the closing tape attached onto the external surface of the jelly-roll. The jelly-roll is formed by laminating the positive electrode plate and the negative electrode plate to be coated with an active material and the separator interposed between the positive electrode plate and the negative electrode plate and by winding the laminated positive electrode plate, the negative electrode plate, and the separator about itself. The closing tape is attached so that it surrounds the external surface of the jelly-roll. The jelly-roll having the attached closing tape is compressed so as to form the electrode assembly.
Although the electrode assembly of the above secondary battery is inserted into the can, since the electrode assembly is not closely attached onto the internal surface of the can, when an external shock is applied to the secondary battery, the electrode assembly vibrates up and down or back and forth in the can. In particular, when the secondary battery is dropped, the electrode assembly vibrates up and down in the can such that the coupling part of the positive electrode tab or the negative electrode tab is separated or such that the electrode assembly is damaged which results in erroneous operation of the battery.